I got a new LCD monitor for my Linux system, however I was concerned I would burn out the backlight because Linux would only blank the screen when the computer was not in use, rather than turn off the monitor completely like Windows did. After some searching, I found out how to make Linux do this very easily. Just follow these three steps:

1) Compile your kernel with ACPI enabled.
I use Gentoo Linux, and the default kernel comes with this already enabled. To check if you have ACPI complied and enabled, see if the file "/proc/acpi/info" exists.

2) Install and run acpid.
On Gentoo, you can install this by running the command "emerge acpid". Then, make it run whenever you boot with the command, "rc-update add acpid default". So that you don't have to reboot, you can now start acpid manually with the command "/etc/init.d/acpid start".

3) Configure XFree86 to use DPMS.
Edit /etc/X11/XF86Config. Add the line 'Option "DPMS"' to the 'Monitor' section of the file. Then add the line 'Option "OffTime" "20"' to the 'ServerLayout' section of the file. The number 20 is the number of minutes of inactivity before the monitor is turned off. It will be turned on when you use the mouse or keyboard again. Optionally, you can use "StandbyTime" for minimal power saving, or "SuspendTime" for moderate power saving. I use "SuspendTime" with my LCD, because they all turn off the backlight, but the other two cause my monitor to say "Lost Signal" for a few seconds first.

To test if everything is working without restarting X and waiting 20 minutes, you can use the command "xset dpms force off" from an xterm. "standby" and "suspend" may be used in place of "off" in that command.

To test if everything is working without restarting X and waiting 20 minutes, you can use the command "xset dpms force off" from an xterm. "standby" and "suspend" may be used in place of "off" in that command.

I believe you do have to restart X, since you've just added the 'Option "DPMS"' line. Otherwise xset won't have any effect.

Great HOWTO Locke. I'd been looking for something like this for a while.

DPMS can't turn off the power to your screen like pressing its power button would do. It can power down the screen into a "sleep" mode to save power, but the screen will never be fully off. I don't know if there's any way to fully power down a monitor other than pressing the power button, although that would be useful for a shutdown script.

I don't know about your monitor but standard monitors can at least switch to a state which is the same as if you power down you computer and the monitor goes off because of no VGA signal. Try "xset dpms force off".

In that state most monitors typically consume less than 0.5W which is something one doesn't really have to bother about IMHO.

Awesome. This is something i've never even realized you could do so easily. Thanks for the post and +1 more for the Documentation, Tips & Tricks section A hint for other users, don't use DMPS like I did, and cause yourself unwanted troubles. Thanks again._________________Ban Reality TV!
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Cheers for this.
I'm trying on my R40 and it still won't turn off the backlight tho.
I'm running through a bundle of tricks to find something that will turn it off but the only thing so far that works under linux is actually pressing the lid switch itself.

Biker: I guess the XF86Config settings are overriden by gnome. Have a look at the gnome screensaver menu. It's in "Desktop-Settings->Complex->Screensaver" (or something similar, mine is in German so I'm not really sure if my back-translation is right ). In that menu there is a tab called "Complex" again in which you can set your power management preferences for gnome.

marshall_j: on my ThinkPad X30 it works without any problems. Maybe you have set your system to first use one of the "higher" power save states? I think the first one only blanks the screen on my X30 but the "off" states switches the backlight off.

however, i have followed the directions and i'm not sure that it is actually being used. my acpid starts fine but if i do a lsmod, none of the acpi modules are loaded. if i modprobe them and then do a lsmod, they all say they are unused....even after restarting the acpid.

i've also tried to just let it sit and wait to see what happens and i don't seem to get any love there either.

i compiled the acpi drivers as modules and i'm running on an inspiron 8600.

Thanks for this tip. I found that when I set things up as you said, the display would automatically turn off when I was in the kdm logon screen, but once I was logged on (to kde in my case), "dpms q" showed that it was disabled.

The solution I found was that you have to go into the "control panel.>power control ->display power control" and set it up there. This overrides the settings from XF86Config.

1) Compile your kernel with ACPI enabled.
I use Gentoo Linux, and the default kernel comes with this already enabled. To check if you have ACPI complied and enabled, see if the file "/proc/acpi/info" exists.

Um, I get stuck on this step. I'm using the 2.6 beta kernel, and I compiled in ACPI. But I still get the system telling me:

#
# Power management options (ACPI, APM)
#
CONFIG_PM=y
# CONFIG_SOFTWARE_SUSPEND is not set
# CONFIG_PM_DISK is not set

#
# ACPI (Advanced Configuration and Power Interface) Support
#
CONFIG_ACPI=y
CONFIG_ACPI_BOOT=y
CONFIG_ACPI_INTERPRETER=y
CONFIG_ACPI_SLEEP=y
CONFIG_ACPI_SLEEP_PROC_FS=y
CONFIG_ACPI_AC=y
CONFIG_ACPI_BATTERY=y
CONFIG_ACPI_BUTTON=y
CONFIG_ACPI_FAN=y
CONFIG_ACPI_PROCESSOR=y
CONFIG_ACPI_THERMAL=y
# CONFIG_ACPI_ASUS is not set
# CONFIG_ACPI_TOSHIBA is not set
# CONFIG_ACPI_DEBUG is not set
CONFIG_ACPI_BUS=y
CONFIG_ACPI_EC=y
CONFIG_ACPI_POWER=y
CONFIG_ACPI_PCI=y
CONFIG_ACPI_SYSTEM=y
# CONFIG_ACPI_RELAXED_AML is not set

#
# APM (Advanced Power Management) BIOS Support
#
# CONFIG_APM is not set

Any ideas?

Steve
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to standby the display after 10 minutes. the off option does not work in my case, it resumes immediatly after it blanked. the standby option does the same for me as the off option is supposed to be - it blanks the screen.
but i have problems with the display syntax: 0:0 does not work for me. for some it works, for some not, dunno why. i tried :0.0 instead, but this works only sometimes, only god knows why. the man page could not help me so maybe you have a solution for this.
i'm asking cause i want to use this for acpi events. i dont whant the display to blank if the ac adaptor is connected, but i want it to blank if it is disconnected.